Firebase user store that derives from a Firebase auth store

user.ts

// SVELTE
import { derived, type Readable } from 'svelte/store';
// FIREBASE
import { onAuthStateChanged } from 'firebase/auth';
import type { Auth, User } from 'firebase/auth';
// LIB
import { firebaseAuth } from '$lib/firebaseAuth';
import { authEmitter } from '$lib/urqlClient';

function newUserStore() {
	// export const user = createUserStore();
	const { subscribe } = derived<Readable<Auth>, User | null>(firebaseAuth, ($auth, set) => {
		onAuthStateChanged($auth, (user) => {
			if (user && user.getIdToken) {
				user
					?.getIdToken()
					.then((token) => {
						authEmitter.emit('token', token);
					})
					.catch((err) => {
						console.log('GET ID TOKEN ERROR');
						console.log(err);
						// todo: handle error
					});
			} else {
				console.log('NO USER');
			}
			set(user);
		});
	});

	// known can be awaited
	const known = new Promise<void>((resolve) => {
		// eslint-disable-next-line @typescript-eslint/no-empty-function
		let unsub = () => {};
		unsub = subscribe((user) => {
			if (user !== null) {
				resolve();
				unsub();
			}
		});
	});

	return {
		subscribe,
		known
	};
}

export const user = newUserStore();